Driving unit for loud-speakers



1929- N. M. MICHAILOVSKY DRIVING UNIT FOR LOUD SPEAKERS Filed Aug. 23. 1928 INVENTOR AT ORNEY Patented Oct. 15, 1929 UNITED STATES PATENT OFFICE- NICHOLAS M. MICHAILOVSKY, OF BRONX, NEVJ YORK, ASSIGNOR, BY DIRECT AND MESNE ASSIGNMENTS, OF THIRTY-SEVEN AND ONE-HALF PER CENT TO PAUL NOEL BITTER, F DOUGLAS MANOR, LONG ISLAND, NEW YORK, AND TV ENTY-FIVE 1?E'.R CENT TO HENRY W. BOETTGER, OF NEW YORK, N, Y.

DRIVING UNIT FOR LOUD-SPEAKERS Application filed August 23, 1928. Serial No. 301,525.

This invention relates to the driving units or motors used for operating loud speakers,

and the objects of the invention are to provide a device of this character, which will be of simple, inexpensive construction and highly eflicient in its operation.

The novel features of the invention by which the foregoing and other desirable objects are attained will be clear from the following specification in conjunction with the drawing accompanying and forming part of the same. I

In the drawing, Fig. 1 is a face view or side elevation of an embodiment of the invention and Fig. 2 is a lower end view of the same, the transmission connections in both views Being broken, for lack of space.

The magnet employed in the present illustration is of the permanent horseshoe type as indicated at 3-and is provided at opposite faces of the same with the pole pieces 4 and 5 secured in place by the through screws 6 and spaced to provide the magnetic gaps 7.

The armature cooperating with the magnet is disclosed as a fiat magnetic bar 8 pivotally supported intermediate its ends on a pin 8 carried by a bridge 9, which is secured to the ends of the yoke by screws 10.

For magnetizing the armature, two inter-v connected coils 11, 12 are shown surrounding the end portions of the armature and held flat against the inside'cheelrs of the pole pieces by being seated in recesses 18 in the opposite faces of the bridge.

To gain a maximum degree of interaction between the armature and pole pieces, the armature is shown as of approximately the same width as the magnetic gaps and as working freely without contact in notches 14 in the ends of the pole tips, which are but slightly wider than the thickness of the adjacent portions of the armature.

W'th this construction, it willbe seen that the magneticfiux across the gap willbe concentrated at the corners of the notches and the adjoining corners of the substantially rectangular fiat armature and that therefore a maximum interaction between armature and pole pieces will be accomplished with the armature in the intermediate or starti I g positransmission connection may be taken oil from a point intermediate the support 8 and the end of the armature so as to gain a certain leverage eilect. l v

The construction it will be observedis particularly simple and the parts may be mounted by the simple act of assemblage. The' clearance between the armature and the notched portions of the pole pieces is relativelyclosc and remains constant because of the parallel motion of the armature into the notches.

The thin fiat form of armature shown is particularly light and sensitive, with but little inertia so that it responds quickly and :truly to the incoming impulses. The struc-' ture as a whole'is compact and takes up but little space for the Work it accomplishes. To hold the armature so that it will at all times work truly in the slots or notches 14, the armature pin or support 8 may be supported at both ends, as indicated in Fig. 1, where the upper end of the pin is shown as having an anchorage or bearing in the raised or trussed like portion 9 of the bridge.

The magnet may be of electromagnetic as well as of the permanent type shown, and if found desirable, may be of the single pole instead of the lei-polar type shown.

lVhat is claimed is:

l. A device oi? the character disclosed, comprising a magnet structure having a pole piece with a parallel sidednotch in the end of the same, an armature mounted for move ment in the direction of extent of said par' allel sided notch and having a garallelsi'ded' portion operating with small clearance withi in said notch, a coil for magnetizing said armature and a power transmission connection extending from said armature v 2. Apparatus of the character disclosed,

- 5 comprising a magnet structure having 0pposed polar projections with aligned parallel sided notches in the opposing edges of thesame, an armature mounted for movement in the direction of extent of said notches and having parallel sided portions of-a size and positioned to operate with small clearance in the notches and a magnetizing coil for said armature and a power transmission connection engaged with said armature.

3. A driving unit for loud speakers or the like, comprising a magnet. yoke, pairs of op posed cooperating pole pieces at opposite faces of said magnet yoke and providing 'magnetic gaps at opposite sides of the mag.-

net structure, the adjacent opposing ends of i *having a portion of less width, parallel with and movingin the notched portions of said pole pieces, a magnetizing coil for said armature and a power transmission connection engaged with the armature. i

5. A driving unit for speakers or the like,

comprising a magnet structure having a tapered polar projection with a parallel sided 0 notch in the end of the same, an armature .mounted for movement in the direction of extent of said parallel sided notch, said armature having a substantially rectangularportion of less width than the notch and mounted '45 with the corner edges of the same opposite tothe cprner edges of the notch in the polar Y projections, a magnetizing coil for the armature and a power transmission connection ex tending from the armature.

6. A driving unit for speakers or the like, comprising a magnet structure having opposed pole pieces spaced to provide a magnetic gap and tapered inwidth down to said gap, the tapered ends of said pole pieces having inwardly extending notches therein, an

' armature mounted for movement between said pole pieces in the direction of extent of said notches and constructed for free movement .in the notches, a power transmission connection engaged with said armature and a magnetizing coil for the armature.

7. A driving unit for speakers or thelike, comprising a magnet yoke, pole pieces applied to. opposite faces and providing-magnetic gaps jat opp osite sides of the yoke, said poleipleces being tapered down to said magnetic gaps and having notches in the tapered ends of the same, an armature mounted for move ment'in'said gaps in the direction of extent of said notches and constructedfor operation in the notches, a power transmission connection engaged with the armauure and means for magnetizing the armature? 8. A construction as in claim 7, in which the magnetizing means includes coils sur rounding the opposite end portionsof the armature and a non-magnetic bridge across the. ends of the yoke supporting said coils and the armature. x

9. A driving unit for speakers or the like, comprising a magnet yoke, pole pieces at opposite 'faces and providing magnetic gaps at opposite sides oi said magnet yoke, said pole pieces being tapered down to said magnetic gaps and having parallel sided notches in the opposing edges thereof, an armature having flat portions to freelyenter said notches, the flat portions of said armature being of approximately the width of. said gaps and the armature being mounted with the corner edges of said flat portions in-oppositlon-to the corner edges of the notches in the. pole pieces, a power transmission connection engaged with the armature, magnetizing coils surrounding the end portions of the armature and means for supporting said coils and said armature in the relations described, said means enabling movement of the armature parallel with the notches in the pole pieces. r v

10. A drivingunit for speakers or the like, comprising a magnet yoke, a bridge member secured across the ends of said yoke and having a trussed up portion, a support held at its opposite ends by the main portion and the trussed up portion of the bridge, an arma ture carried by the intermediate portion of said support between the main portion and trussed portions, a magnetizing coil for said armature, a power transmission element 'connected with said armatureand pole pieces at the sides of the yoke and between which the trussed'portion ,of the bridge is located.

In testimony whereof I aflix my signature.

NICHOLAS M. MIOHAILOVSKY. 

